1. Field of the Invention
The present invention relates to polyimides. In particular, it relates to polyimides containing the pentafluorosulfanylbenzene moiety.
2. Description of Related Art
Polyimides containing a trifluoromethyl moiety have been prepared from the diamine, 3,5-diaminobenzotrifluoride (DABTF), which contains one symmetrically substituted, polar CF.sub.3 group. These polymers are more soluble, have greater optical transparency and lower dielectric constants than state-of-the-art polyimides. The glass transition temperatures (Tg) of these polymers are similar to those prepared from m-phenylenediamine and they also exhibit high thermooxidative stability. These polymers are easily processible due to their enhanced solubility and are useful in any electronic and aerospace applications where high thermooxidative stability, optical transparency and excellent dielectric characteristics are needed.
Despite these properties, there is a desire to have a polymer which not only has low dielectric properties but a higher Tg, higher density, and lower solubility than those of the CF.sub.3 containing polyimides. This combination of properties would allow the polymer to be used at higher temperatures, harsher environments, and in applications where polymer to substrate compatibility is important such as piezoelectric applications.
An object of the present invention is to prepare polyimide polymers containing a pentafluorosulfanylbenzene moiety.
Another object of the present invention is to prepare polyimide polymers which exhibit high Tg, high density, low solubility, and low dielectric properties.